Protection method and protection system of ship's power distribution system

Abstract

A protection system of ship's power distribution system, when a fault occurs in the feeder preset to be in charge of the third circuit breaker module, the relay of the third circuit breaker module trips the circuit breaker based on a magnitude and a direction of a fault current, and to transmit a power distribution maintenance signal to the relay of the second circuit breaker module. When a fault occurs in the switchboard preset to be in charge of the second circuit breaker module, the relays of the second and third circuit breaker modules trip the circuit breaker based on a magnitude and a direction of a fault current and the relay of the second circuit breaker module transmit a power distribution maintenance signal to the relay of the third circuit breaker module preset based on the magnitude and direction of the fault current.

What is claimed is: 
     
         1 . A system for protecting a power distribution system of a ship, the system comprising:
 a first circuit breaker module having a circuit breaker disposed between a generator and a switchboard to block transmitted power and a relay configured to control an operation of the circuit breaker;   a second circuit breaker module having a circuit breaker disposed on the switchboard to block transmitted power and a relay configured to control an operation of the circuit breaker; and   a third circuit breaker module having a circuit breaker disposed between the switchboard and a feeder to block transmitted power and a relay configured to control an operation of the circuit breaker,   wherein the relay of the second circuit breaker module and the relay of the third circuit breaker module have the same delay time,   when a fault occurs in the feeder preset to be in charge of the third circuit breaker module, the relay of the third circuit breaker module is configured to trip the circuit breaker based on a magnitude and a direction of a fault current, and to transmit a power distribution maintenance signal to the relay of the second circuit breaker module, and   when a fault occurs in the switchboard preset to be in charge of the second circuit breaker module, the relays of the second and third circuit breaker modules are configured to trip the circuit breaker based on a magnitude and a direction of a fault current, and the relay of the second circuit breaker module is configured to transmit a power distribution maintenance signal to the relay of the third circuit breaker module preset based on the magnitude and direction of the fault current.   
     
     
         2 . The system of  claim 1 , wherein the relay of the first circuit breaker module, the relay of the second circuit breaker module, and the relay of the third circuit breaker module are configured to communicate with each other to identify a position and a direction of a fault current. 
     
     
         3 . The system of  claim 1 , wherein a delay time of the relay of the first circuit breaker module is longer than delay times of the relay of the second circuit breaker module and the relay of the third circuit breaker module. 
     
     
         4 . The system of  claim 1 , wherein the second circuit breaker module includes at least one circuit breaker disposed between adjacent switchboards among a plurality of switchboards, and a relay configured to control an operation of the at least one circuit breaker for each space between the adjacent switchboards among the plurality of switchboards. 
     
     
         5 . The system of  claim 1 , wherein the second circuit breaker module includes two circuit breakers disposed between adjacent switchboards among a plurality of switchboards, and two relays configured to respectively control operations of the two circuit breakers for each space between the adjacent switchboards among the plurality of switchboards. 
     
     
         6 . A method for protecting a power distribution system of a ship, the method comprising:
 a first operation in which a first circuit breaker module having a circuit breaker disposed between a generator and a switchboard to block transmitted power and a relay configured to control an operation of the circuit breaker, a second circuit breaker module having a circuit breaker disposed on the switchboard to block transmitted power and a relay configured to control an operation of the circuit breaker, and a third circuit breaker module having a circuit breaker disposed between the switchboard and a feeder to block transmitted power and a relay configured to control an operation of the circuit breaker, relays of the first circuit breaker module, the second circuit breaker module, and the third circuit breaker module communicate with each other to identify a magnitude and a direction of a fault current when a fault occurs in the power distribution system of the ship;   a second operation in which the circuit breaker module is instantaneously tripped when the identified magnitude and direction of the fault current correspond to a preset differential protection fault;   a third operation in which the relay of the third circuit breaker module trips the circuit breaker and transmits a power distribution maintenance signal to the relay of the second circuit breaker module when the identified magnitude and direction of the fault current do not correspond to the differential protection fault and correspond to a preset feeder fault;   a fourth operation in which a fault location is identified based on the identified magnitude and direction of the fault current when the identified magnitude and direction of the fault current do not correspond to the differential protection fault and the feeder fault, the relays of the second and third circuit breaker modules connected to the switchboard in which a fault occurs are configured to trip the circuit breaker, when the fault occurs in the switchboard preset to be in charge of the second circuit breaker module, and the relay of the second circuit breaker module is configured to transmit a power distribution maintenance signal to the relay of the third circuit breaker module preset based on the magnitude and direction of the fault current; and   a fifth operation in which the circuit breaker of the first circuit breaker module of the switchboard in which the fault occurs is tripped.   
     
     
         7 . The method of  claim 6 , wherein
 in the first operation, the relay of the second circuit breaker module and the relay of the third circuit breaker module have the same delay time, and a delay time of the relay of the first circuit breaker module is set to be slower than delay times of the relay of the second circuit breaker module and the relay of the third circuit breaker module.